Note: Descriptions are shown in the official language in which they were submitted.
.4 CA 02627050 2012-04-24
A PAPER SUBSTRATE HAVING ENHANCED PRINT DENSITY
Field of the Invention
The present invention relates to a sizing composition that, when applied to
paper
substrate, creates a substrate, preferably suitable for inkjet printing,
having increased
print density, print sharpness, low HST, and/or image dry time, the substrate
preferably having high brightness and reduced color-to-color bleed as well. In
addition, the present invention relates to a method of reducing the HST of a
paper
substate by applying the sizing composition to at least one surface thereof.
Further, the
application relates to methods of making and using the sizing composition, as
well as
methods of making and using the paper containing the sizing composition.
Background of the Invention
Ink jet recording systems using aqueous inks are now well known. These
systems usually generate almost no noise and can easily perform multicolor
recordings for business, home and commercial printing applications. Recording
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CA 02627050 2012-04-24
sheets for ink jet recordings are known. See for example U.S. Pat. Nos.
5,270,103;
5,657,064; 5,760,809; 5,729,266; 4,792,487; 5,405,678; 4,636,409; 4,481,244;
4,496,629; 4,517,244; 5,190,805; 5,320,902; 4,425,405; 4,503,118; 5,163,973;
4,425,405; 5,013,603; 5,397,619; 4,478,910; 5,429,860; 5,457,486; 5,537,137;
5,314,747; 5,474,843; 4,908,240; 5,320,902; 4,740,420; 4,576,867; 4,446,174;
4,830,911; 4,554,181; 6,764,726 and 4,877,680
However, conventional paper substrates, such as those above remain poor in
balancing good print density, HST, color-to-color bleed, print sharpness,
and/or
image dry time. Accordingly, there is a need to provide such high-performance
functionality to paper substrates useful in inkjet printing, especially those
substrates
preferably having high brightness.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: A first schematic cross section of just one exemplified embodiment
of the
paper substrate that is included in the paper substrate of the present
invention.
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Figure 2: A second schematic cross section ofjust one exemplified embodiment
of the
paper substrate that is included in the paper substrate of the present
invention.
Figure 3: A third schematic cross section of just one exemplified embodiment
of the
paper substrate that is included in the paper substrate of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have discovered a sizing composition that, when
applied to paper or paperboard substrates, improves the substrate's print
density,
color-to-color bleed, print sharpness, and/or image dry time. Further, the
paper
substrate preferably has a high brightness.
The sizing composition may contain a pigment. Examples of pigments are
clay, calcium carbonate, calcium sulfate hemihydrate, and calcium sulfate
dehydrate, calcium carbonate, preferably precipitated calcium carbonate, in
any
form including ground calcium carbonate and silica-treated calcium carbonate.
When the pigment is a calcium carbonate, it may be in any form. Examples
include
ground calcium carbonate and/or precipitated calcium carbonate. Commercially
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S. CA 02627050 2012-04-24
available products that are preferred are those offered as JetcoatTm 30 from
Specialty
Minerals Inc., Jetcoat MD1093 from Specialty Minerals Inc., XC3310-1 from
Omya Inc, and OmyaJetTM B5260, C4440 and 6606 from Omya Inc.
The pigment may have any surface area. Those pigments having a high
surface area are included, including those having a surface area of greater
than 20
square meters/gram, preferably greater than 30 square meters/gram, more
preferably
greater than 50 square meters/gram, most preferably greater than 100 square
meters/gram. This range includes greater than or equal to 1, 5, 10, 15, 20,
25, 30,
35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100 square meters/gram,
including any
and all ranges and subranges contained therein.
The sizing composition may contain a pigment at any amount. The
composition may include from 0 to 99wt% based upon the total weight of the
solids
in the composition, preferably at least 15wt%, more preferably at least 30wt%,
most
preferably at least 45wt% pigment based upon the total weight of the solids in
the
composition. This range may include 0, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45,
50, 55,
60, 65, 70, 75, 80, 85, 90, 100wt% of pigment based upon the total weight of
the
solids in the composition, including any and all ranges and subranges
contained
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CA 02627050 2012-04-24
therein. The most preferred amount being about 52 wt% pigment based upon the
total weight of the solids in the composition.
The sizing composition may contain a binder. Examples of binders include,
but are not limited to, polyvinyl alcohol, AmresTm (a Kymene type), Bayer
ParezTM,
polychloride emulsion, modified starch such as hydroxyethyl starch, starch or
derivatives thereof including cationic and oxidized forms and from corn and/or
potato for example, polyacrylamide, modified polyacrylamide, polyol, polyol
carbonyl adduct, ethanedial/polyol condensate, polyamide, epichlorohydrin,
glyoxal, glyoxal urea, ethanedial, aliphatic polyisocyanate, isocyanate, 1,6
=
hexamethylene diisocyanate, diisocyanate, polyisocyanate, polyester, polyester
resin, polyacrylate, polyacrylate resin, acrylate, and methacrylate. While any
combination of binders may be used, one embodiment includes a sizing
composition
containing starch or modifications thereof combined with polyvinyl alcohol as
multi-component binder.
=
When there is a multicomponent binder system, one embodiment relates to a
system including at least starch and deriviates thereof with polyvinyl
alcohol. In this
embodiment, the ratio of starch/PV0H solids based on the total weight of the
solids
in the sizing composition may be any ratio so long as both are present in the
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composition. The sizing composition may contain a ratio of starch/PVOH wt%
solids based on the total weight of the solids in the composition of from 99/1
to
1/99, preferably from 50/1 to 1/5, more preferably at most 10/1 to 1:2, most
preferably at most 8/1 to 1/1. This range includes 99/1, 50/1, 25/1, 15/1.,
10/1, 9/1,
8/1, 7/1, 6/1, 5/1, 4/1, 3/1, 2/1, 1/1, 2/3, 1/2, 1/10, 1/25, 1/50, 1/99,
including any
and all ranges and subranges therein. The most preferred starch/PVOH ratio
being
6/1.
When polyvinyl alcohol is utilized in the sizing solution and/or in the paper,
polyvinyl alcohol (PVOH) is produced by hydrolyzing polyvinyl acetate (PVA).
The acetate groups are replaced with alcohol groups and the higher the
hydrolysis
indicates that more acetate groups have been replaced. Lower
hydrolysis/molecular
weight PVOH are less viscous and more water soluble. The PVOH may have a
%hydrolysis ranging from 100% to 75%. The % hydrolysis may be 75, 76, 78, 80,
82, 84, 85, 86, 88, 90, 92, 94, 95, 96, 98, and 100%hdrolysis, %, including
any and
all ranges and subranges therein. Preferably, the % hydrolysis of the PVOH is
greater than 90%.
The sizing composition may contain a binder at any amount. The sizing
composition may contain at least one binder from 0 to 99wt%, preferably at
least
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lOwt%, more preferably at least 20wt%, most preferably at least 30 wt% based
on
the total weight of the solids in the composition. This range may include 0,
1, 5, 10,
15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100wt% based
on the
total weight of the solids in the composition, including any and all ranges
and
subranges contained therein. The most preferred being about 37wt% binder based
on the total weight of the solids in the composition.
In one embodiment, when the sizing composition contains a binder and a
pigment, the weight ratio of the binder/pigment may be any ratio. The binder
pigment weight ratio may be from 99/1 to 1/99, preferably from 50/1 to 1/10,
more
preferably from 25/1 to 1/5, most preferably from 10/1 to 1/3. This range
includes
99/1, 50/1, 25/1, 10/1, 5/1, 2/1, 1/1, 1/2, 2/3, 1/3, 1/4, 1/5, 10/1, 25/1,
50/1, and
99/1, including any and all ranges and subranges therein. The most preferred
binder/pigment weight ratio is 7/10.
The sizing composition may contain at least one nitrogen containing organic
species. Exemplified nitrogen containing organic species are compounds,
oligomers and polymers are those containing one or more quaternary ammonium
functional groups. Such functional groups may vary widely and include
substituted
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CA 02627050 2012-04-24
and unsubstituted amines, imines, amides, urethanes, quaternary ammonium
groups,
dicyandiamides and the like. Illustrative of such materials are polyamines,
polyethyleneimines, polymers and copolymers of diallyldimethyl ammonium
chloride (DADMAC), copolymers of vinyl pyrrolidone (VP) with quatemized
diethylaminoethylmethacrylate (DEAMEMA), polyamides, cationic polyurethane
latex, cationic polyvinyl alcohol, polyalkylamines dicyancliamid copolymers,
amine
glycigyl addition polymers, poly[oxyethylene (dimethyliminio) ethylene
(dimethyliminio) ethylene] dichlorides. Examples of nitrogen containing
species
include those mentioned in US Patent Number 6,764,726.
The most preferred nitrogen
containing species are polymers and copolymers of diallyldimethyl ammonium
chloride (DADMAC).
The sizing composition may contain at least one nitrogen containing organic
species at any amount. The sizing composition may contain the nitrogen
containing
species at an amount ranging from 0 to 99wt%, preferably from 0.5 to 50wt%,
more
preferably from 1 to 20 wt %, most preferably from 2 to 10 wt% based on the
total
weight of the solids in the composition. This range may include 0, 0.5, 1, 2,
3, 4, 5,
6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85,
90, 100wt%
based on the total weight of the solids in the composition, including any and
all
WO 2007/053681 CA 02627050 2008-04-23 PCT/US2006/042645
ranges and subranges contained therein. In a preferred embodiment, the
composition contains about 8wt% of the nitrogen containing species based on
the
total weight of the solids in the composition.
The sizing composition may contain at least one inorganic salt. Suitable
inorganic salts may be monovalent and/or divalent and/or trivalent and may
contain
any level of hydration complexes thereof. Exemplified inorganic salts are
those
from Groups 1, 2 and 13 from the Periodic Table of Elements and hydrated
complexes thereof, including monohydrates, dihydrates, trihydrates,
tetrahydrates,
etc. The cationic metal may be sodium, calcium, magnesium, and aluminum
preferably. The anionic counterion to the cationic metal of the inorganic salt
may be
any halogen such as chloride, boride, fluoride, etc and/or hydroxyl group(s).
The
most preferred inorganic salt being sodium chloride.
The sizing composition may contain at least one inorganic salt at any amount.
The sizing composition may contain from 0 to 99wt%, preferably from 0.25 to 25
wt%, more preferably from 0.5 to 5, most preferably from 1 to 3 wt% of the
inorganic salt based on the total weight of the solids in the composition.
This range
may include 0, 0.25, 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40,45, 50,
55, 60, 65,
70, 75, 80, 85, 90, 100wt% based on the total weight of the solids in the
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CA 02627050 2012-04-24
composition, including any and all ranges and subranges contained therein. In
a
preferred embodiment, the sizing composition contains about 2.5wt% of the
inorganic salt based on the total weight of the solids in the composition.
The sizing composition may contain at least one optical brightening agent
(OBA). Suitable OBAs may be those mentioned in USSN 60/654,712 filed
February 19, 2005, and US? 6,890,454.
The OBAs may be commercially available from
Clariant. Further, the OBA may be either cationic and/or anionic. Example OBA
is
that commercially available LeucophoreTM BCW and Leucophore FTS from Clariant.
In one embodiment, the OBA contained in the sizing composition is cationic.
= The sizing composition may contain any amount of at least one anionic OBA.
The sizing composition may contain anionic OBA at an amount from 0 to 99wt%,
preferably from 5 to 75wt%, more preferably from 10 to 50 wt%, most preferably
from 20 to 40wt% based on the total weight of the solids in the composition.
This
range may include 0, 1, 5, 10, 15, 20,25, 30, 35, 40, 45, 50, 55, 60, 65, 70,
75, 80,
85, 90, 99wt% anionic OBA based on the total weight of the solids in the
composition, including any and all ranges and subranges contained therein. In
a
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preferred embodiment, the sizing composition contains about 35wt% of anionic
OBA based on the total weight of the solids in the composition.
The sizing composition may contain any amount of at least one cationic
OBA. The sizing composition may contain cationic OBA at an amount from 0 to
99wt%, preferably from 0.5 to 25wt%, more preferably from 1 to 20 wt%, most
preferably from 5 to 15wt% based on the total weight of the solids in the
composition. This range may include 0, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45,
50, 55,
60, 65, 70, 75, 80, 85, 90, 99wt% anionic OBA based on the total weight of the
solids in the composition, including any and all ranges and subranges
contained
therein. In a.preferred embodiment, the sizing composition contains about 8wt%
of
cationic OBA based on the total weight of the solids in the composition.
The present invention also relates to a paper substrate containing any of the
sizing compositions described above.
The paper substrate contains a web of cellulose fibers. The source of the
fibers may be from any fibrous plant. The paper substrate of the present
invention
may contain recycled fibers and/or virgin fibers. Recycled fibers differ from
virgin
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fibers in that the fibers have gone through the drying process at least once.
The paper substrate of the present invention may contain from 1 to 99 wt%,
preferably from 5 to 95 wt%, most preferably from 60 to 80 wt% of cellulose
fibers
based upon the total weight of the substrate, including 1, 5, 10, 15, 20, 25,
30, 35,
40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 99 wt%, and including any
and all
ranges and subranges therein.
While the fiber source may be any, the preferable sources of the cellulose
fibers are from softwood and/or hardwood. The paper substrate of the present
invention may contain from 1 to 100 wt%, preferably from 5 to 95 wt%,
cellulose
fibers originating from softwood species based upon the total amount of
cellulose
fibers in the paper substrate. This range includes 1, 2, 5, 10, 15, 20, 25,
30, 35, 40,
45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100wt%, including any and all
ranges
and subranges therein, based upon the total amount of cellulose fibers in the
paper
substrate.
The paper substrate of the present invention may contain from 1 to 100 wt%,
preferably from 5 to 95 wt%, cellulose fibers originating from hardwood
species
based upon the total amount of cellulose fibers in the paper substrate. This
range
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includes 1, 2, 5, 10, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80,
85, 90, 95,
and 100wt%, including any and all ranges and subranges therein, based upon the
total amount of cellulose fibers in the paper substrate.
When the paper substrate contains both hardwood and softwood fibers, it is
preferable that the hardwood/softwood ratio be from 0.001 to 1000. This range
may
include 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 15,
20, 25, 30,
35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500,
600, 700,
800, 900, and 1000 including any and all ranges and subranges therein and well
as
any ranges and subranges therein the inverse of such ratios.
Further, the softwood and/or hardwood fibers contained by the paper
substrate of the present invention may be modified by physical and/or chemical
means. Examples of physical means include, but is not limited to,
electromagnetic
and mechanical means. Means for electrical modification include, but are not
limited to, means involving contacting the fibers with an electromagnetic
energy
source such as light and/or electrical current. Means for mechanical
modification
include, but are not limited to, means involving contacting an inanimate
object with
the fibers. Examples of such inanimate objects include those with sharp and/or
dull
edges. Such means also involve, for example, cutting, kneading, pounding,
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CA 02627050 2012-04-24
impaling, etc means.
Examples of chemical means include, but is not limited to, conventional
chemical fiber modification means including crosslinking and precipitation of
complexes thereon. Examples of such modification of fibers may be, but is not
limited to, those found in the following patents 6,592,717, 6,592,712,
6,582,557,
6,579,415, 6,579,414, 6,506,282, 6,471,824, 6,361,651, 6,146,494, H1,704,
5,731,080, 5,698,688, 5,698,074, 5,667,637, 5,662,773, 5,531,728, 5,443,899,
5,360,420, 5,266,250, 5,209,953, 5,160,789, 5,049,235, 4,986,882, 4,496,427,
4,431,481, 4,174,417, 4,166,894, 4,075,136, and 4,022,965.
Further modification of fibers is
found in United States Patent Applications having Application Number
60/654,712
filed February 19, 2005; 11/358,543 filed February 21, 2006; 11/445,809 filed
June
2, 2006; and 11/446,421 filed June 2, 2006, which may include the addition of
optical brighteners (i.e. OBAs) as discussed therein, which are hereby
incorporated,
in their entirety, herein by reference.
One example of a recycled fiber is a "fine". Sources of "fines" may be found
in SaveAll fibers, recirculated streams, reject streams, waste fiber streams.
The
amount of "fmes" present in the paper substrate can be modified by tailoring
the
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rate at which such streams are added to the paper making process.
The paper substate preferably contains a combination of hardwood fibers,
softwood fibers and "fines" fibers. "Fines" fibers are, as discussed above,
recirculated and are any length. Fines may typically be not more that 100 um
in
length on average, preferably not more than 90 pm, more preferably not more
than
80 pm in length, and most preferably not more than 75 pm in length. The length
of
the fines are preferably not more than 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,
55, 60,
65, 70, 75, 80, 85, 90, 95, and 100 pm in length, including any and all ranges
and
subranges therein.
The paper substrate may contain fines at any amount. The paper substrate
may contain from 0.01 to 100 wt% fines, preferably from 0.01 to 50wt%, most
preferably from 0.01 to 15wt% based upon the total weight of the fibers
contained
by the paper substrate. The paper substrate contains not more than 0.01, 0.05,
0.1,
0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50,
55, 60, 65, 70,
75, 80, 85, 90, 95 and 100wt% fines based upon the total weight of the fibers
contained by the paper substrate, including any and all ranges and subranges
therein.
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The paper substrate may also contain an internal sizing and/or external sizing
composition. The internal sizing composition may be applied to the fibers
during
papermaking at the wet end, while the external sizing composition may be
applied
to the fibers via a size press and/or coater. The above mentioned sizing
compositions of the present invention may be the internal and/or external
sizing
composition contained by the paper substrate of the present invention.
Figures 1-3 demonstrate different embodiments of the paper substrate 1 in the
paper substrate of the present invention. Figure 1 demonstrates a paper
substrate 1
that has a web of cellulose fibers 3 and a sizing composition 2 where the
sizing
composition 2 has minimal interpenetration of the web of cellulose fibers 3.
Such
an embodiment may be made, for example, when a sizing composition is coated
onto a web of cellulose fibers.
Figure 2 demonstrates a paper substrate 1 that has a web of cellulose fibers 3
and a sizing composition 2 where the sizing composition 2 interpenetrates the
web
of cellulose fibers 3. The interpenetration layer 4 of the paper substrate 1
defines a
region in which at least the sizing solution penetrates into and is among the
cellulose fibers. The interpenetration layer may be from 1 to 99% of the
entire cross
section of at least a portion of the paper substrate, including 1, 2, 5, 10,
15, 20, 25,
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30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 99% of the paper
substrate,
including any and all ranges and subranges therein. Such an embodiment may be
made, for example, when a sizing composition is added to the cellulose fibers
prior
to a coating method and may be combined with a subsequent coating method if
required. Addition points may be at the size press, for example.
Figure 3 demonstrates a paper substrate 1 that has a web of cellulose fibers 3
and a sizing solution 2 where the sizing composition 2 is approximately evenly
distributed throughout the web of cellulose fibers 3. Such an embodiment may
be
made, for example, when a sizing composition is added to the cellulose fibers
prior
to a coating method and may be combined with a subsequent coating method if
required. Exemplified addition points may be at the wet end of the paper
making
process, the thin stock, and the thick stock.
The paper substrate may be made by contacting any component of the sizing
solution with the cellulose fibers consecutively and/or simultaneously. Still
further,
the contacting may occur at acceptable concentration levels that provide the
paper
substrate of the present invention to contain any of the above-mentioned
amounts of
cellulose and components of the sizing solution. The contacting may occur
anytime
in the papermaking process including, but not limited to the thick stock, thin
stock,
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CA 02627050 2012-04-24
head box, and coater with the preferred addition point being at the thin
stock.
Further addition points include machine chest, stuff box, and suction of the
fan
pump. Preferably, the components of the sizing solution are preformulated
either
together and/or in combination within a single and/or separate coating
layer(s) and
coated onto the fibrous web via a size press and/or coater.
The paper or paperboard of this invention can be prepared using known
conventional techniques. Methods and apparatuses for forming and making and
applying a coating formulation to a paper substrate are well known in the
paper and
paperboard art. See for example, G.A. Smook referenced above.
All such known methods
can be used in the practice of this invention and will not be described in
detail.
The paper substrate may contain the sizing composition at any amount. The
paper substrate may contain the sizing composition at an amount ranging from
70 to
300 lbs/ton of paper, preferably from 80 to 2501bs/ton of paper, more
preferably
from 100 to 200 lbs/ton of paper, most preferably from 125 to 175 lbs/ton of
paper.
This range includes, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,
190,
200, 210, 220, 230, 240, 250, 260, 270 280, 290, and 300 lbs/ton of paper,
including
any and all ranges and subranges therein. In a preferred embodiment the paper
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substrate contains a size press applied sizing composition at an amount of 150
lbs/ton of paper substrate.
Given the above mentioned preferred amounts of sizing composition
contained in the substrate of the present invention, combined with the above-
mentioned amounts of pigment, binder, nitrogen containing compound, and
inorganic salt; the amounts of each of the pigment, binder, nitrogen
containing
compound, inorganic salt that are contained in the paper may be easily
calculated.
For example, if 50wt% of pigment is present in the sizing solution based upon
the
total weight of solids in the composition, and the paper substrate contains
1501bs of
the sizing composition/ton, then the paper substrate contains 50% x 1501bs/ton
of
paper= 75 lbs pigment/ton of paper, which is 75 lbs/20001bs x 100= 3.75wt%
pigment based upon the total weight of the paper substrate.
The paper substrate contains any amount of at least one pigment. The paper
substrate may contain from 0.5 wt % to 10 wt%, preferably from 1 to 8wt%, more
preferably from 1.5 to 6wt%, most preferably from 2 to 5wt% of pigment based
upon the total weight of the substrate. This range includes 0.5, 1, 1.5, 2,
2.5, 3, 3.5,
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4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 and lOwt% of pigment based upon
the total
weight of the substrate, including any and all ranges and subranges therein.
The paper substrate contains any amount of at least one binder. The paper
substrate may contain from 0.1 wt % to 7 wt%, preferably from .2 to 5wt%, more
preferably from 0.3 to 3wt%, most preferably from 1 to 3 wt% of binder based
upon
the total weight of the substrate. This range includes 0.1, 0.2, 0.3, 0.4,
0.5, 1, 1.5, 2,
2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, and 7.5wt% of binder based upon the
total weight
of the substrate, including any and all ranges and subranges therein.
The paper substrate contains any amount of at least one nitrogen containing
compound. The paper substrate may contain from 0.01 wt % to 5 wt%, preferably
from 0.05 to 2wt%, more preferably from 0.1 to 1.5 wt%, most preferably from
0.25
to 1 wt% of nitrogen containing compound based upon the total weight of the
substrate. This range includes 0.01, 0.02, 0.03, 0.05, 0.07, 0.1, 0.2, 0.3,
0.4, 0.5,
0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, and 3wt%
of nitrogen
containing compound based upon the total weight of the substrate, including
any
and all ranges and subranges therein.
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The paper substrate contains any amount of at least inorganic salt. The paper
substrate may contain from 0.001 wt % to 3 wt%, preferably from 0.01 to
2.5wt%,
more preferably from 0.02 to 1 wt%, most preferably from 0.05 to 0.5 wt% of
inorganic salt based upon the total weight of the substrate. This range
includes
0.001, 0.002, 0.005, 0.007, 0.01, 0.02, 0.03, 0.05, 0.06, 0.07, 0.08, 0.09,
0.1, 0.2,
0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6,
2.8, and 3wt%
of inorganic salt based upon the total weight of the substrate, including any
and all
ranges and subranges therein.
The paper substrate may contain any amount of OBA. The OBA may be
cationic and/or anionic. The OBA may be supplied by the sizing composition as
mentioned above and/or within the substrate itself. For example, the OBA may
be
premixed with the fibers at the wet end of the papermaking and even before the
headbox. Preferred examples of using OBA:fiber mixes is found in United States
Patent Applications having Application Number 60/654,712 filed February 19,
2005; 11/358,543 filed February 21,2006; 11/445,809 filed June 2,2006; and
11/446,421 filed June 2, 2006..
In one embodiment of the present invention, the paper substrate contains
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WO 2007/053681 CA 02627050 2008-04-23PCT/US2006/042645
internal OBA and externally applied OBA. The internal OBA may be cationic or
anionic, but is preferably anionic. The externally applied OBA may be cationic
or
anionic, but is preferably cationic. The externally applied OBA is preferably
applied as a member of the sizing composition at the size press as mentioned
above
in the above preferred amounts of OBA. However, external OBA may also be
applied at the coating section.
The paper substrate of the present invention may have any amount of OBA.
In one embodiment, the OBA is present in as sufficient amount so that the
paper has
at least 80% GE brightness. The GE brightness is preferably at least 80, 85,
90, 91,
92, 93, 94, 95, 96, 97, 98, 99, and 100%, including any and all ranges and
subranges
contained therein.
Further, the paper may have a suitable amount of OBA and other additives
(such as dyes) so that the paper preferably has a CIE whiteness of at least
130. The
CIE whiteness may be at least 130, 135, 140, 145, 150, 155, 160, 65, 170, 175,
180,
185, 190, 195, and 200 CIE whiteness points, including any and all ranges and
subranges therein.
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WO 2007/053681 CA 02627050 2008-04-23PCT/US2006/042645
In one embodiment, the substrate contains an effective amount of OBA. An
effective amount of OBA is such that the GE brightness is at least 90,
preferably at
least 92, more preferably at least 94 and most preferably at least 95%
brightness.
The OBA may be a mixture of the above-mentioned internal and externally
applied
OBA, whether cationic and/or anionic so long as it is an effective amount.
The density, basis weight and caliper of the web of this invention may vary
widely and conventional basis weights, densities and calipers may be employed
depending on the paper-based product formed from the web. Paper or paperboard
of
invention preferably have a final caliper, after calendering of the paper, and
any
nipping or pressing such as may be associated with subsequent coating of from
about 1 mils to about 35 mils although the caliper can be outside of this
range if
desired. More preferably the caliper is from about 4 mils to about 20 mils,
and most
preferably from about 7 mils to about 17 mils. The caliper of the paper
substrate
with or without any coating may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 17,
20, 22, 25, 27, 30, 32, and 35, including any and all ranges and subranges
therein.
Paper substrates of the invention preferably exhibit basis weights of from
about 10 lb/3000ft 2 to about 500 lb/3000ft 2, although web basis weight can
be
outside of this range if desired. More preferably the basis weight is from
about
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WO 2007/053681 CA 02627050 2008-04-23PCT/US2006/042645
301b/3000ft 2 to about 200 lb/3000ft 2, and most preferably from about 35
lb/3000ft
2 to about 150 lb/3000ft 2. The basis weight may be 10, 12, 15, 17, 20, 22,
25, 30,
32, 35, 37, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120,
130, 140,
150, 160, 170, 180, 190, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425,
450, 500
lb/3000ft 2, including any and all ranges and subranges therein.
The final density of the papers may be calculated by any of the above-
mentioned basis weights divided by any of the above-mentioned calipers,
including
any and all ranges and subranges therein. Preferably, the final density of the
papers,
that is, the basis weight divided by the caliper, is preferably from about 6
lb/3000ft
2/mil to about 14 lb/3000ft 2/mi1 although web densities can be outside of
this range
if desired. More preferably the web density is from about 7 lb/3000ft 2/mil to
about
13 lb/3000ft 2/mil and most preferably from about 9 lb/3000ft 2/mil to about
12
lb/3000ft 2/mil.
The web may also include other conventional additives such as, for example,
starch, expandable microspheres, mineral fillers, bulking agents, sizing
agents,
retention aids, and strengthening polymers. Among the fillers that may be used
are
organic and inorganic pigments such as, by way of example, polymeric particles
such as polystyrene latexes and polymethylmethacrylate, and minerals such as
24
CA 02627050 2012-04-24
calcium carbonate, kaolin, and talc. Other conventional additives include, but
are
not restricted to, wet strength resins, internal sizes, dry strength resins,
alum, fillers,
pigments and dyes. Internal sizing helps prevent the surface size from soaking
into
the sheet, thus allowing it to remain on the surface where it has maximum
effectiveness. The internal sizing agents encompass any of those commonly used
at
the wet end of a paper machine. These include rosin sizes, ketene dimers and
multimers, and alkenylsuccinic anhydrides. The internal sizes are generally
used at
levels of from about 0.00 wt. % to about 0.25 wt. % based on the weight of the
dry
paper sheet. Methods and materials utilized for internal sizing with rosin are
discussed by E. Strazdins in The Sizing of Paper, Second Edition, edited by W.
F.
Reynolds, Tappi Press, 1989, pages 1-33. Suitable ketene dimers for internal
sizing
are disclosed in U.S. Pat. No. 4,279,794;
and in United Kingdom Patent Nos. 786,543; 903,416; 1,373,788 and
1,533, 434, and in European Patent Application Publication No. 0666368 A3.
Ketene dimers are commercially available, as Aquapel® and Precis®
sizing agents from Hercules Incorporated, Wilmington, Del. Ketene multimers
for
use in internal sizes are described in: European Patent Application
Publication No.
0629741A1,
European Patent Application Publication No. 0666368A3,
25
CA 02627050 2012-04-24
and U.S. patent No. 5,846,663.
Alkenylsuccinic anhydrides for internal sizing are disclosed in U. S. Pat. No.
4,040,900 and by C. E.
Farley and R. B. Wasser in The Sizing of Paper, Second Edition, edited by W.
F.
Reynolds, Tappi Press, 1989, pages 51-62. A variety of alkenylsuccinic
anhydrides
are commercially available from Albemarle Corporation, Baton Rouge, La.
The paper substrate may be made by contacting further optional substances
with the cellulose fibers as well. The contacting of the optional substances
and the
cellulose fibers may occur anytime in the papennaking process including, but
not
limited to the thick stock, thin stock, head box, size press, water box, and
coater.
Further addition points include machine chest, stuff box, and suction of the
fan
pump. The cellulose fibers, components of the sizing composition, and/or
optional
components may be contacted serially, consecutively, and/or simultaneously in
any
combination with each other. The cellulose fibers components of the sizing
composition may be pre-mixed in any combination before addition to or during
the
paper-making process.
The paper substrate may be pressed in a press section containing one or more
nips. However, any pressing means commonly known in the art of papermaking
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WO 2007/053681 CA 02627050 2008-04-23 PCT/US2006/042645
may be utilized. The nips may be, but is not limited to, single felted, double
felted,
roll, and extended nip in the presses. However, any nip commonly known in the
art
of papermaking may be utilized.
The paper substrate may be dried in a drying section. Any drying means
commonly known in the art of papermaking may be utilized. The drying section
may include and contain a drying can, cylinder drying, Condebelt drying, IR,
or
other drying means and mechanisms known in the art. The paper substrate may be
dried so as to contain any selected amount of water. Preferably, the substrate
is
dried to contain less than or equal to10% water.
The paper substrate may be passed through a size kress, where any sizing
means commonly known in the art of papermaking is acceptable. The size press,
for example, may be a puddle mode size press (e.g. inclined, vertical,
horizontal) or
metered size press ( e.g. blade metered, rod metered). At the size press,
sizing
agents such as binders may be contacted with the substrate. Optionally these
same
sizing agents may be added at the wet end of the papelinaking process as
needed.
After sizing, the paper substrate may or may not be dried again according to
the
above-mentioned exemplified means and other commonly known drying means in
the art of papeinialcing. The paper substrate may be dried so as to contain
,any
27
CA 02627050 2012-04-24
selected amount of water. Preferably, the substrate is dried to contain less
than or
equal to10% water. Preferably, the sizing apparatus is a puddle size press.
The paper substrate may be calendered by any commonly known calendaring
means in the art of papermaking. More specifically, one could utilize, for
example,
wet stack calendering, dry stack calendering, steel nip calendaring, hot soft
calendaring or extended nip calendering, etc. While not wishing to be bound by
theory, it is thought that the presence of the expandable microspheres and/or
composition and/or particle of the present invention may reduce and alleviate
requirements for harsh calendaring means and environments for certain paper
substrates, dependent on the intended use thereof.
The paper substrate may be microfinished according to any microfinishing
means commonly known in the art of papermaking. Microfinishing is a means
involving frictional processes to finish surfaces of the paper substrate. The
paper
substrate may be microfinished with or without a calendering means applied
thereto
consecutively and/or simultaneously. Examples of microfinishing means can be
found in United States Published Patent Application 20040123966 and references
cited therein, as well as USSN 60/810181 filed on June 2, 2006.
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The Hercules Sizing Test Value ("HST") of the substrate is selected to
provide the desired waterfastness characteristics. The HST is measured using
the
procedure of TAPPI 530 pm-89. The paper substrate of the present invention may
have any HST. In some embodiments, the HST may be as much as 400, 300, 200,
and 100 seconds. Further, the HST may be is as low as 0.1, 1, 5 and 10
seconds.
However, in a preferred embodiment of this invention, the HST is less than 10
seconds, preferably, less than 5 seconds, more preferably less than 3 seconds
HST,
most preferably less than about 1 second. The HST may be 0.001, 0.01, 0.05,
0.1,
0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4,4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 and
10 seconds,
including any and all ranges and subranges therein. As it is well known to
those of
ordinary skill in the art, the HST will vary directly with the basic weight of
the
substrate and other factors known to those of ordinary skill in the art. Based
upon
the foregoing infoimation, one of ordinary skill in the art can use
conventional
techniques and procedures to calculate, determine and/or estimate a particular
HST
for the substrate used to provide the desired image waterfastness
characteristics.
The paper substrate of the present invention may have any black optical
density as measured by TAPPI METHOD T 1213 sp-03. The black optical density
may be from 0.5 to 2.0, more preferably from 1.0 to 1.5. The black optical
density
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may be 0.5, 0..6, 0.7, 0.8, 0.9, 1.0, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10,
1.11, 1.12,
1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.3, 1.4, and 1.5, including
any and all
ranges and subranges therein.
From density, one can naturally calculate waterfastness using the following
equation:
(OD of soaked ink area/OD of unsoaked ink area) * 100 = % Waterfastness.
The paper substrate of the present invention may have any waterfastness. The
paper
substrate may have a waterfastness of at least 90%, preferably at least 95%,
more
preferably greater than 98%, most preferably greater than 100%, including any
and
all ranges and subranges therein.
In one embodiment of the present invention, the paper substrate may contain
an effective amount of pigment and binder. An effective amount of pigment and
binder is that which bestows on the paper a black optical density that is at
least 1.0,
preferably from 1 to 2, more preferably from 1 to 1.5 and most preferably from
1.1
to 1.3, including any and all ranges and subranges therein.
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The present invention relates to a method of decreasing the HST of a paper
substrate. Preferably, the above-mentioned sizing composition is contacted
with a
substrate having a first HST and containing a web of cellulose fibers and
optional
substances mentioned above at a size press or coating section so as to prepare
a
paper substrate having a second HST that is less than the first HST and
containing
the sizing composition, the web of cellulose fibers, and optional substance.
While
the second FIST is less than the first HST, the present invention preferably
reduces
the first FIST by at least 10%, more preferably by at least 25%, most
preferably by
at least 50%. This reduction range may be at least 10, 15, 20, 25, 30, 35, 40,
45, 50,
60, 75, 80, 95 and 99% of the first HST, including any and all ranges and
subranges
therein.
The present invention is explained in more detail with the aid of the
following embodiment example which is not intended to limit the scope of the
present invention in any manner.
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CA 02627050 2012-04-24
EXAMPLES
Example 1
The following size press formulations were prepared for treating the un-
surface sized base paper.
Table 1
Chemicals 1 2 3 4 5 6 7
Jetcoat MD1093 Precipitated 100 100 100
calcium carbonate
XC3310-1, ground calcium 100 100
carbonate
TX-75NX, silica treated calcium 100
carbonate
TX-75ZX silica treated calcium 100
carbonate
Polyvinyl alcohol 20 10 10 10 10
Oxidized starch 30 60 60 100 =
Cationic starch 100 60
Polydadmac 10 10 10 10 10
Calcium chloride 5 5 5 5 5
%solids 13 13 13 13 13 13 13
PH 6.7 7.0 7.3 7 6.9 6.8 6.9
Brookfiled viscosity 27 46 80 55 118 38 27
Temperature, F 117 120 117 130 130 130 130
The pigmented size press formulations were applied to an unsurface sized 90
gsm base paper
using a rod metering size press. The target coat weight or pick up is 6 gsm.
Calendering was
done on a steel-to-steel lab calender at room temperature with a nip pressure
of 90 psi. The
smoothness target is 125 Sheffield smoothness.
Table 2
The paper samples from example 1 were evaluated for print performance on an
Kodak
Versamark 5000 digital press. Excellent print quality were obtained. The print
density test results
on the trial samples provided in example 1 are listed in the following table.
Condition Print Density on Kodak
Versamark 5000
1 1.15
2 1.12
3 1.13
4 1.09
1.11
6 1.18
7 1.14
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WO 2007/053681
PCT/US2006/042645
Example 2:
Paper substrates having a basis weight of 24 lb/1300 square feet were made and
a
sizing composition was applied thereto both surfaces of the paper substrate at
size
press. The sizing compositions applied to the paper substrate are those
according to
the following Table 2.
Table 2
functionality Chem \ Prop'ties 1 2 3 4
5
\ Cond'ns
SP puddle puddle Puddle puddle puddle
configuration
pigment (2) 5MI JetCoatO 100
30
SMI MD 1093 100 100 100 100
Binder (2) Clinton 442 60 60 60 60
60
starch
Mowiol 28-99 10 10 10 10 , 10
fixative (2) Gen Floc F71100 10
Cartafix VXZ 10 10 15 15
salt (2) NaCI 8 8 8 8
8
CaCl2 5
brightener Leucophore 100
(2) BCW (wet pts)
Leucophore FT5 20 20 20 20
(wet pts)
Wet-xer (1) Amres 24HP 5
5
properties target %solids 15 15 15 15
15
actual %solids 15.2 15.1 15.1 15.1 15.3
Brookfield #2 122 160 89 76 61
@ 50 rpm
Brookfield #2 100 125 84 70 69
@ 100 rpm
PH 8.0 7.3 7.8 7.8 7.0
temperature 109 112 147 140 143
Pickup 4.8 4.6 4.6 5.0 4.9
(lbs/3,300 ft2)
pickup (gsm) 7.1 6.8 6.8 7.4 7.25
pickup (lbs/ton 157 151 151 164 161
of paper)
33
CA 02627050 2012-04-24
Oboriral 1.15/1.14 1.13/1.14 1.23/1.19 1.22/1.17 1.20/1.17
Obookadmal 1.13/1.19 1.14/1.19 1.22/1.19 1.22/1.17 1.19/1.17
Obbleedral 0.26/0.33 0.44/0.48 0.13/0.11 0.04/0.12 0.08/0.18
%Bleedm 22.83/29.13 39.26/42.00 10.35/8.85 276/10.41 6.42/15.47
%H20fastness01 97.78/104.08 100.98/105.05 99.60/100.42 100.14/100.15
99.31/100.15
Gen F1OcTM F71100 (General Chemicals) and CartafixTM VXZ (Clariant) are both
of the
chemical nature of poly(dadmac) and are nitrogen-containing species.
AmresTM, a kymene wet-strength resin from Kamira is also nitrogen-containing
species.
MowiolTM 28-99 (Clariant) is a version of PVOH, which is 99% hydrolyzed and is
of
high molecular weight.
Starch and PVOH were cooked separately and diluted to a solids level of about
15%. Each of the formulation was prepared in accordance with the recipe as
tabulated above and was thoroughly mixed together.
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An overall %solids was first arrived at greater than the targeted 15%, because
the
rest of the ingredients all have a solids level above 15%.
For each of the formulations, the actual initial %solids was measured and then
diluted, as close as possible, to 15%. Each of the formulations was sent to
the 14"
pilot size press, which was pre-configured to CS puddle operation.
The paper after size press was dried to 4.2 to 5.0% moisture.
The subscript [a] denotes average, which means each of the numbers was
averaged
from 4 or even more readings.
The two numbers before and after the slash sign represent readings from the
two
sides of the paper, respectively.
Ink jet print densities are measured by means of optical densities with an X-
rite densitometer. The density according to TAP P1 METHOD T 1213 sp-03 is the
optical -negative logarithm to base 10 of transmittance for transparent
material or
= 35
CA 02627050 2012-04-24
the reflectance for an opaque material and has the equation Optical Density =
log10
1/R, where R = Reflectance. The following densitometer was used: X-Rite
Densitometer, manufactured byX-Rite Inc. Density is a function of the
percentage
of light reflected. From this density procedure, one can easily measure
Waterfastness and % bleed as well using the following equations:
Calculation for % Waterfastness:
(OD of soaked ink area/OD of unsoaked ink area)* 100 = c1/0 Waterfastness
Calculation for % Bleed:
[(OD near soaked ink area ¨ OD of paper)/OD unsoaked ink area] * 100 =
% Bleed.
Numerous modifications and variations on the present invention are possible
in light of the above teachings. It is, therefore, to be understood that
within the
scope of the accompanying claims, the invention may be practiced otherwise
than as
specifically described herein.
As used throughout, ranges are used as a short hand for describing each and
every value that is within the range, including all subranges therein.
36
